Devices of the type comprising an air intake chamber provided with an inlet for outside air, with an inlet for recirculated air and with at least one flap which can selectively control said inlets, as well as a motor-driven fan unit which is arranged downstream of the air intake chamber and comprises a casing accommodating a centrifugal turbine which is driven by a motor, is provided with blades and can take in an air flow axially then deliver it tangentially to a heating and/or air-conditioning unit are known.
In a device of this type, the air intake chamber is supplied with a flow of outside air and/or of recirculated air which is then delivered under pressure by the motor-driven fan unit, also referred to as a blower, to the heating and/or air-conditioning unit which has at least one heat exchanger (heating radiator and, optionally, evaporator) for heating or cooling the air flow which is then to be sent to the passenger compartment of the vehicle through various distribution pipes and outlets.
The casing of the motor-driven fan unit customarily has a peripheral spiral which, with an increasing cross-section, encloses the turbine and can divert the air flow thus delivered into the tangential direction.
In known devices, the motor of the motor-driven fan unit is generally arranged on the opposite side from the air inlets of the air intake chamber, so that the air flow can enter the casing of the motor-driven fan unit through a circular opening which, at the same time, constitutes the exit of the air intake chamber.
This solution is favorable for supplying the casing of the motor-driven fan unit with air, but has the drawback of increasing the axial space taken up by the casing, because of the layout of the motor.
Furthermore, this layout of the motor, which is then generally located on the same side as the passenger compartment, generates noise which can propagate with ease into the passenger compartment through the various distribution pipes.
Another drawback of this known solution is that it is difficult to provide means for taking the motor-driven fan unit apart easily.
It has also been proposed to locate the motor of the motor-driven fan unit on the same side as the outside-air inlet and the recirculated-air inlet. However, this further solution has substantially the same drawbacks as the solution mentioned above, because of the respective positions of the air inlets.